docs(adr): halkyon.li at home through ramiel, and the Instance console (ADR 0039, 0040)

ADR 0039: the family's instance halkyon.li on balthasar, with Learn, Todo,
Train, Meditate and Jellyfin, sign-up by approval through SimpleLogin alone,
published through ramiel by WireGuard with TLS passed through by name
(HAProxy), the CI runner moved there in a nightly window, deployed by hand.
Supersedes ADR 0032, whose server end goes with sahaquiel.

ADR 0040: one Instance row in every app's Settings opening a route with
accounts, sign-up, assistants, regions and state; the instance's settings in
a file outside the backups, the keys staying in assistants.env; regions from
CoMaps' polygons, which the sidecars build themselves.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

docs/adr/0032-jellyfin-at-home.md

@@ -3,6 +3,9 @@
 - **Status:** decided 30 Oct 2026, by the developer (D1, D9 and D10 their own choices,
   D2–D8 agreed as recommended). Built the same day (*As built*, below); not brought up
   yet, which takes the developer's steps as root on the instance's server.
+  **Superseded** on 8 Nov 2026 by ADR 0039: its server end, learn.halkyon.eu's server,
+  is retired, and Jellyfin becomes halkyon.li's own sidecar on the machine that was its
+  home end. Its open question goes with it. The files are removed once ADR 0039 is built.
 - **Builds on:** the Jellyfin sidecar (`deploy/compose.jellyfin.yaml`,
   `deploy/sidecars/README.md`, decided 14 Oct 2026) and Halkyon Learn's suggested
   server (`JellyfinSuggestion`, decided 13 Oct). Train's Jellyfin (ADR 0030, D47, D52,